Oxy-penicillins



Patented July 3i, 1951 UNITED STATES PATENT o'r'r'ucr.

2,5 2,410 OXY-PENICILLINS T Y Otto K. Behrens, Reuben G. Jones, and Quentin F. Soper, Indianapolis, Ind., and Joseph W. Gorse, Lafayette, Calif., assignors to Eli Lilly and Company, Indianapolis, Ind., a corporation of Indiana No Drawing. Application May 3, 1949,

Serial No. 91,215

7 Claims. (Cl. 260-239.1)

This invention relates to antibiotic compounds cillin to the substantial exclusion of the known 1 and is directed to novel oxy-penicillins. This ap- I plication is a continuation-in-part of our copen ding prior applications Serial Nos. 653,136 and 653,137, filed March 8, 1946, now Patents Nos. 2,479,295 and 2,479,296 respectively, and Serial Nos. 773,448 and 773,449, filed September 11, 1947, now abandoned.

There are certain known penicillins comprising a group of chemically related compounds which, under suitable conditions of growth, are produced as metabolic products by a penicillin-producing mold. The complete molecular structures of these compounds had not been definitely established when said prior applications were filed but suflicient elucidation of structure had been accomplished to allow the assignment to them of the following empirical formula in which R0 has the same meaning as set forth above.

We have made the surprising discovery that a penicillin-producing mold may be induced to produce a novel penicillin, by incorporating in the nutrient medium wherein the moldis grown, a selected organic compound, called herein a precursor compound.' Such selected precursor compound, although foreign to the normal metabolic requirements of the mold, may be metabolized and incorporated in substantial part in the molecule of a novel penicillin. This result is especially surprising in view of the recognized specificity of the enzyme systems whereby lower organisms maintain growth and development. It is further surprising that use of' a selected precursor compound'may lead to the production of a novel peniand normally-produced penicillins.

The present invention contemplates novel products of fermentative processes which com- 1 prise growing a penicillin-producing mold in assoelation with a culture medium containing nutrient material and a selected precursor compound, said product consisting essentially of a penicillin represented by the formula in which R is a radical of the class consisting of aliphatic radicals containing from 2 to 6 carbon f atoms and phenyl radicals which are not more than monos'ubstituted. Aliphatic radicals which, 1 R represents include the alkyl radicals from ethyl through hexyl, al'kylene radicals, for example allyl, 2-methylallyl, butene-2-yl, etc., and substituted alkyl and alkylene radicals, for example, Z-chloroethyl, Z-bromoallyl, 3-ch1oroallyl, Phenyl radicals which R- represents include the phenyl radical itself, and monosubstituted phenyl radicals, for example, the halophenyl radicals,

tolyl, methoxyphenyl, hydroxyphenyl, and nitro- Preferably the-mon'osubstituent onsub-v stituted' phenyl radicals is at the para or metav phenyl.

position.

The novel penicillins are ordinarily produced in the form of a salt, for example the sodium-- salt of the pinicillin acid. The salt may be either-1 the salt originally produced or a difierent salt to which the original product is transformed, and

preferably is one of the salts ordinarily em ployed in the administration of the known penicillins, such as the common metal salts, for example, the sodium salt, the potassium salt, the ammonium salt, the calcium salt, etc.

According to the present knowledge of the structure of penicillin, the products of this application, as defined above, including both acids. .1 and salts thereof, may be represented by the following structural formula s R-o-oHl-t :-Nn,-o1r c ownol 1 I--- H t $00K in which R has thesame meaning as before, and

in which X represents hydrogen when the penicillin is in acid form and represents a salt-forming radica1 when the penicillin is in a salt form,

such salt-forming radical including those ordinarily employed in penicillin production and therapy, such as potassium, sodium, ammonium,

etc.

etc.

the R() radical is the n-hexyloxy radi c al is" named n-hexyloxy-penicillin; and a pe'nicillin wherein the R-O radical is the m-chlorophenoxy radical, /051151. m-ch'lorophenoxypenicillin.

Broadly speaking, a method of producing a novel penicillin in accordance with this inven- 4 found to be particularly suitable is from 24-26 C. The period of time during which the mold is grown will depend upon the objective desired. Thus the mold may be grown only during the period" of" itsmax'imum. rate of growth before mold. row th is interrupted preliminary to isolat1ng the new penicillin. Such a period generally is from 2 to 3 days. On the other hand, the mold may be grown for a longer period of time to obtain the maximum yield of new penicillin. In such a case, mold growth is usually continued for about 4i to 5 days.

Themold'maybe grown under various conditions. For example, the mold may be grown tion is as follows: There is provided a nutrient m without,agitation of -the culture medium, in

" medium suitable for thgrowifi of a penicillinproducing mold. To the nutrient medium is added in effective amount a precursor compound comprising an R-O-- monosubstituted acetic acid or its equivalent. Precursor compounds useful for-this purpose comprise monosubstituted acetic acids represented bythe formula wherei-nzR has the; same meaning as before. In place of the monosubstituted acetic acids, there may. be used equivalents of such acetic acids, said' equivalents comprising those compounds readily converted by the moldrtov the monosubstituted acetic acids. Such equivalents include simple derivatives of the acids such as their salts; esters, amides, and anhydrides, and may include other compounds, which the mold may convert to the monosubstituted acetic acids, such as WE-substituted, saturated straight-chain alcohols, amines, aldehydes, and acids containing an even number of carbon atoms, and the simple derivatives thereof.

The culture medium composition comprising nutrient material and precursor compound is inoculated with a penicillin-producing mold and the m'old is grown under penicillin-producing conditions, during which growtha new penicillin is produced by the mold as a. metabolic product. After mold growth, the mold mycelium is separated from the culture medium, and from the latter the novel penicillin is separated.

The isolation of the new penicillin maybe effectedby methods known to the art, such as adsorption and extraction, to obtain a product sufficiently pure for practical purposes; If a purer product is desired, the new'penicillin may be subjectedto additional methods of purification such as partition chromatography and elution, and recrystallization.

The novel=penicillin desirably is recovered-inthe form of one of its salts; for example the sodium orpotassium salt; Identification of the novel penicillin may be confirmed by methods known to the art, such methods comprising analysis, spectroscopic absorption, X-ray diffraction and antibacterial tests.

The nutrient material used in the composition wherein the. moldis grown may comprise ingredients such as water, sugars, inorganic salts and desirably one" or more indeterminate compositions such as corn steep amino acids and bran. Numerous suitablenutrient media comprising. materials of. the. type mentioned are known to. the art.

Duringthe growth. of the mold the culture medium comprising nutrient material and precursor compound is maintained at a suitable temperature, for example, in the range. of -30 C. The range of temperature which has been which case the mold grows on the surface of the medium. Alternatively, the culture medium may be agitated by shaking or stirring during the growth of the mold in which case the mold is dispersed throughout the culture medium and grows while so dispersed.

The molds suitable for the purposes of this invention are mold organisms of the type capable of producing penicillins. Such organisms include molds of the. Penicillium notatumchrysogenum group as well ascertain moldsof the Aspergillus group. It is to be understood that not all mold strains are equally efficient for the purpose of this invention. By way of example, mold strains suitable for the purposes of this'invention are those known" as strains X1612 and Q176 of the- Penicilliwm notatum chrysogenum group and strain G147 of. the Aspergillus fla'uus group.

The concentration of. the precursor compounds employed inthe culture medium may vary over a substantial range. The precursor compounds may be present in theculture medium in concentrations of the order of about 1 percent, but it is usually desirable that smaller concentratime be employed since there is no particular advantage to' be gained in employing concentrations in substantial excess of thosenecessary to produce the optimum efiect. It appears at present that the optimum concentration of the monosubstituted acetic acids and derivatives thereof lies in the range of about 0.01 to about 0.05 percent on a weight-volume basis when mold strain X1612 is used, and that this optimum concentration may range upwardly when mold strain Q17 6 is used.

The precursor compound may be associated with the mold and culture medium at any suitable time. Thus the materials of the nutrient medium may be inoculated with the mold and the precursor compound to be employed may be incorporated either before or after inoculation of the culture medium with the mold.

The following specific examples further illustrate the invention.

Example 1 The sodium salt of phenoxy-penicillin represented by the'formula can beprepared in the following'manner:

A culture medium is prepared in the following proportions:

Lactose -g Corn steep solids g' Calcium carbonate g 75 N-(Z-hydroxyethyl) -phenoxyacetamide g 0.78

Water. -cc 5000 The culture medium is distributed in 200' cc. 7. .7 The sodium salt of phenoxy-penicillin assayed portions in 1 liter Erlenmeyer flasks, sterilized, about 1660 Oxford units per milligram when inoculated with a spore suspension of Penicillium tested against Staph. aureus, strain 209P. A mold, strain N. R. R. L. 1976, and stoppered with differential assay when carried out on Staph. cotton plugs. The flasks are. maintained at a aureus, strain 209P, and B. subtilis, strain N. R. temperature of about 23-26" C. and shaken con- R. L. B-558, gave a value of about 0.87. Analysis stantly for five days. The flask contents' are thkilglred the presence of 51.17 percent carbon, 4.49 filtered to remove the mold mycelium, the filtrate ent liydrogen, 7.59 percent nitrogen and 8.50 cooled to about 0 C., acidified to about pH 2.2 percentsdlfunw mnd ith th mmat d with orthophosphoric acid and shaken with an values of 51.34 perceift earw percent hyequal volumedf amyl acetate. The amyl acetate drogen, 7.55 percent nitrogen an '8=6-1..percent layer is separated and extracted with three suc- Sulfur s cessive'lOO cc. portions of cold water to which cold N/lO sodium bicarbonate solution is added during the course of each extraction until a pH of about 7.0 to 7.3 is attained in the aqueous phase. The aqueous extracts are combined, cooled to about 0 C" acidified to about pH 22 A culture medmm is prepared as in Example 1 and is placed in a 5 gallon bottle equipped with with orthophosphoric acid and extracted successively with three 100 cc. portions of ether. The stirrer and an an mlet tube fitted with an ether extracts are combined, and are passed air filter through a chromatographic type silica adsorp The culture medium is sterilized and inoculated tion column about mm. in diameter and 250 mm. long and containing a pH 6.2 phosphate buffer. The silica column is developed by per- 5 colation with six 100 cc. portions of ether containing successively increasing amounts of methanol in the order of 1, 1 2, 2 and 3 percent.

The developed silica column is divided into 30 about 12 equal sections and each section is eluted with three 30 cc. portions of M/15 phosphate Example 2 be prepared as follows:

strain X1612. The bottle contents are maintained at a temperature of about 23-26 C. and are continuously stirred for five days. Throughthe air inlet tube. The mold mycelium is then removed from the aqueous broth by filtration, and the filtrate is treated as in Example 1 to isolate and purify the phenoxy-penicillin. The sodium salt of phenoxy-penicillin thus prepared bufier of pH 7b. The eluates ar e assayed the slanie as that prepared by the procedure of teriologically to determine their penicillin conamp 8 tent. Most of the antibiotic activity is found 5 in certain of the sections, and the eluates from these sections are combined, cooled to about 0 C. and acidified to about pH 2.2 and extracted with three cc. portions of chloroform. The Y, combined chloroform extracts are passed through 5 a silica adsorption column containing a pH 6.2 phosphate buffer. This silica column is developed by'per'colation With three 150 cc. portions of is prepared by th 'procedure ofExam'ple 1 using chloroform containing successively increasing N-(2-hydroxyethyl) -p-methoxyphenoxy acetamamounts of methanol in the order oil, 2 and ide as the precursor in the proportion of 180 3 P e The developed S l column is then mg. ,per liter of culture medium. In a preparadivided into 12 equal sectionsand each section is eluted with three 30 cc. portions of M/ 1 Ph chromatographic column was found to contain a p ate buffer of D Again most of the antiband of antibiotic activity at the upper portion biotic activity originates in certain of the sections 50 of th l W e t t i recovered of the col and the eluates from these from this band was passed through the chlorotions are combined, cooled to about 0 C., acidified form bufier chromatographic column, t t to about pH 2.2 and extracted with three 100 cc. ity was found divided into two portions, one on Demons of etherether extracts are a column, and one in the development solvent. bined and extracteiwlth f 75 of 1 cold This latter was recovered and crystallized from dmite aqueous splutlon of P hydroxlde. to acetone by the procedure set forth in Example 1 whlch N/10 Sodmm hydroxlde 18 added durmg The crystalline material was recrystallized five the course of the extraction so that a final pH of about To is attained in the aqueous phase times from 90 percent acetone by the addition From the aqueous solution, the sodium salt of 60 of ajbsolPte acetoPei and the P' l phenoxy-penicillin may be prepared by any suit- Pemcmm Obtamed assayed 1120 um'frs p r m able means, for example by freezing and evaporaand gave a differential assay value of 0.92. Analt in vacuo fro t frozen t t ysis showed the presence of 6.35 percent nitrogen The sodium salt thus obtained is purified by and 7.14 p nt m th y as mpa d with caldissolving it in 2 cc. of absolute acetone from oulated values of 6.96 percent nitrogen and 7.71 which upon standing it separates in crystalline percent methoxyl. form. It is separated by centrifugation and washed with small portions of absolute acetone. It is then dissolved in about 3 cc. of 85 percent aqueous acetone, the solution filtered and 4 cc. 7 of absolute acetone added to the filtrate whereupon the pure crystalline material separates. The salt is recrystallized by dissolving it in about desired in the pe c l Th s, h f ll n 3 cc. of 85 percent aqueous acetone followed by other new oxy-penicillins are prepared using the the addition of about 7 cc. of absolute acetone. precursors listed.

Example 3 lin represented by the formula omoQo-wmmmsm Example 4 Other oxy-penicillins of our invention are prepared by the procedures of the foregoing examples, using precursors containing the oxy radical The sodium salt of phenoxy-penicillin can also 7 with a spore suspension of Penicillium mold;

out thistime, air is continuously passed through The sodium salt of p-methoxyphenoxy-peniciltion thus carried out, the ether-buffer (pH 6.4)'

-New Pcn'icillins Precursors for-the NewTeniciHins p-tolyloxy-penicillin. m-tolyloxy-penicillin p-bromophenoxy-pen n m-chlorophenoxy-penicillinl p-nitrophenoxy-penicillinl ethoxy-penicillin allyloxy-penicillin. n-butoxy-penicillin isoamyloxy-peniclllig ethoxyacctigacid flllSLlOXYBQB UC acid; mbutoxyacetic ac isosxnyloxyacetic acid N Q-hydroxyethyl)-p-tolyloxyacetemide N-(2-hydroxyethyl)-mtolyloxyaceternide N-(Q-hydroxyethyl) -p-bromophenox5;acetamide N-(m-chlorophcnoxyacetyl)-dl-vali.ue N-(2-hydrcxyethyl)-p;nitropheuoxyacetamide Example 5 The new penicillin s qbtained in the form of their sodium salts maybe c0nvertd"t6otlir salts in a number of ways. One way is as follows: An aqueous solution of the sodium salt, acidified to about pH 2, is extracted with an equalvolume of an organic solvent, such as amyl acetate, ether, chloroform, or the like. The organic solvent solution, containing the new penicillin in acid form, is extracted with'an aqueous solution containing the cation of the desired salt, for example, a solution of potassium hydroxide, calcium phosphate, ammonium hydroxide, or the like, at about pH 8.5. The aqueous extract contains the penicillin as the corresponding salt, for example, the potassium salt, thecalcium salt, or the ammonium salt of the peni- Y cillin, andsuch salt. is suitably recovered from the solution, as by drying in vacuo from the frozen state.

We claim as our invention:

1. A compound of the group consisting of a" new penicillin acid and its sodium, potassium, calcium and ammonium salts, said acid being represented by the formula s R-0cH,%-NH-oH-o owHo,

|| 0 COOH in which R is a radical of the class consisting of aliphatic hydrocarbon radicals having from 2 to 6 carbon atoms, the phenyl radical, and-monosubstituted phenyl radicals in which the substituent is a member of the group consisting of lower aliphatic hydrocarbon, lower aliphatic hydrocarbon ether, nitro, and halogen substituentsnfi, W ,7

2. A new penicillin re miasentedby the formul'a o s Ahphatic-O-CHa- -NHoH-( C(CHQ;

coon in which aliphatic" is an aliphatic hydrocarbon radical having from 2'to 6 carbon atoms. V g

3. A new penicillin represented by the formula Aliphatic-0 The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,479,295 Behrens et al Aug. 16, 1949 

1. A COMPOUND OF THE GROUP CONSISTING OF A NEW PENICILLIN ACID AND ITS SODIUM, POTASSIUM, CALCIUM AND AMMONIUM SALTS, SAID ACID BEING REPRESENTED BY THE FORMULA 